How does Solar Activity affect GNSS?
There are many, many papers on this subject that can offer you a lot of depth on this subject; just google “solar cycle GPS.” In my Eric Gakstatterish sort of way, I’ll write a brief description of how it affects GNSS. The effect on GPS signals as they pass through the ionosphere is the largest single source of error that we see in GNSS today. Essentially, free electrons contained in the ionosphere affect the propagation of the signal as it passes through. Since the signals are traveling at the speed of light and GNSS is based on nanosecond timing, it doesn’t take much interference to introduce error. For a graphic and more detailed information on the ionosphere, click here. Modeling the Total Electron Content (TEC) of the ionosphere is something you may have heard of when reading about GNSS. TEC is directly affected by solar activity, and thus the solar cycle. The solar cycle is an 11-year cycle of solar activity. Following is a nice graphic from the U.S. National Oceanic and Atmosphe
